Xoxicalco was one of the main leading centres of the Mexican Central Altiplane, after the fall of Teotihuacan. Its characteristics define a period of the Mesoamerican history known as “Epiclassic”, dated between 700 and 900 A.D. This period was characterized by a marked militarism, migration, political and economical instability, fortification of the cities, on the principle of worshipping war gods and a mixture of cultures. One of the most likely reasons to have chosen the site construction place is that the area was a strategic point of economical and political control în the Morelos Valley. The Xocicalco builders have changed and adapted the mountainous area to build terraces on which they later built temples, pyramids, great palaces, ceremonial areas, tanks, pelota fields or tunnels, which were then used as astronomical observatories, everything according to a complex urban plan, which covered almost four square kilometres. The area was the scene of some violent conflicts of the internal caste, the traces of fires proving this, which along with the external conflicts, led in the end to the final departure from that place. Xoxicalco – Feathered Serpent’s Pyramid.Keywords: Xocicalco, Central Altiplane, epiclassic, pyramids, pelota game, astronomic observatories